My inlaws expects me to remember their birthdays, anniversary but when it's my birthday they never wish me. On my anniversary too they wish my husband and not me. I find them to be too egoist and I get irritated by their behaviour. What to do to not get stressed?

Just let it go. Be the bigger person and don't let these things bother you. It's not worth it, I feel. Getting upset on your birthday or anniversary because some people forget (whether it is intentional or not) is not worth it especially when there are sooo many other people in your life who care and love you. If you show you are upset, then you'll be immature. So be the bigger person and smile it off :)